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Showing posts from January, 2014
direct path reads
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To resolve the direct path reads wait event :- Please check the below views :- V$SESSION_EVENT -> to identify sessions with high numbers of waits V$SESSTAT -> to identify sessions with high "physical reads direct" (statistic only present in newer Oracle releases) V$FILESTAT -> to see where the IO is occurring V$SQLAREA -> for statements with SORTS and high DISK_READS (which may or may not be due to direct reads) Solution approcah :- If the file indicates a temporary tablespace check for unexpected disk sort operations. Ensure Parameter DISK_ASYNCH_IO -> is TRUE . Ensure the OS asynchronous IO is configured correctly. Check for IO heavy sessions / SQL and see if the amount of IO can be reduced.Better approach will be to look at the sql query that need to be tuned and need to run in parallel . Please check with ASH reports to see the all the queries which have this particular wait event . Ensure no disks are IO bound. And in t...
Significant Virtual Memory Paging on Linux When None is Occurring in ADDM Reports
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There will be Significant Virtual Memory Paging on Linux When None is Occurring in ADDM Reports. There may be following message in the ADDM report: From the ADDM report FINDING 1: 100% impact (48628 seconds) -------------------------------------- Significant virtual memory paging was detected on the host operating system. RECOMMENDATION 1: Host Configuration, 100% benefit (32719 seconds) ACTION: Host operating system was experiencing significant paging but no particular root cause could be detected. Investigate processes that do not belong to this instance running on the host that are consuming significant amount of virtual memory. Also consider adding more physical memory to the host. First, review the following bugs which incorrectly show large swapping statistics that may cause incorrect ADDM message as per above message. And if applicable, apply the bugs. For 10.2.0.5, for Linux: Note:12347332.8 Bug 12347332 - V$OSSTAT / ADDM incor...